Inheritance, Variation and Evolution Flashcards
What is a Phenotype?
Physical appearance of the genes.
What is a gene?
Controls a characteristic
What is a allele?
Different forms of a gene
What does it mean if a phenotype is DOMINANT?
Characteristic is dominant even if allele is present on 1 chromosome.
What does it mean by a phenotype is RECESSIVE?
Allele must be on both chromosomes.
What is a genotype?
Alleles for a gene.
What is Homozygous?
2 IDENTICAL alleles for a characteristic.
What is Heterozygous?
2 DIFFERENT alleles for a characteristic.
Where does Meiosis occur?
In the testes or ovaries.
What are the steps of Meiosis?
- Diploid (2n) cell from either testes or ovaries will contain 46 chromosomes.
- Each Chromosome duplicates its genetic material
- Each duplicated chromosome inherited from mother pairs up with the same duplicated chromosome inherited from the father.
- Each chromosome pair is separated and the cell divides
- Now there are two cells with either maternally or paternally inherited chromosome. All chromosomes line up centrally
- Each duplicated copy is separated as these cells complete the second meiosis division.
From 1 cell there are now 4 cells each of which has half (haploid, n) number of chromosomes as the original and are genetically different.
Differences in Mitosis and Meiosis?
Any of these:
Mitosis make 2 cells / Meiosis makes 4 cells
Mitosis divides once / Meiosis divides twice
Mitosis cells are diploids (2n) at the end / Meiosis cells are haploids (n) 23 in the end.
Mitosis has no variation in cells / Meiosis does have variation in cells
Meiosis does not increase species survival chance / Meiosis increases species survival chance due to natural selection,
Mitosis has fast reproduction / Meiosis has slower reproduction.
Mitosis is used for growth + repair / Meiosis is used to produce gametes (Sperm + Egg).
Order in sizes of smallest to biggest:
Gene
DNA
Nucleus
Chromosome
DNA
Gene
Chromosome
Nucleus
What is a genome?
The ENTIRE GENETIC makeup of an organism.
What are the uses of understanding genomes?
Learning genome of other organisms can lead to us understanding causes of communicable disease.
Understand inherited diseases.
Tracing genomes away from common ancestors.
How many pairs of chromosomes are there in human cells?
23
What is Polydactyly?
When you are born with extra fingers or toes?
What type of allele is Polydactyly?
Dominant - Only needs to be inherited by 1 parent
hat is the genotype of an individual who is homozygous recessive for polydactyl?
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How is cystic fibrosis caused?
Causes by a mutation in a protein in the cell membranes.
What does happens to a person with Cystic fibrosis?
Mucus is thick and sticky (usually meant to be runny)
Causes germs to stay in the stomach leading to a infection.
Can cause breathing difficulties.
Can cause Pancreatic duct to become blocked so food struggles to digest.
What allele is Cystic Fibrosis caused by?
Caused by a recessive allele.
What are the chances of cystic fibrosis to be inherited with heterozygous dominant alleles.
25%
What the different type of Screening for genetic disorders?
- DNA analysis of IVF embryo cell.
- DNA Analysis of cells from the placenta.
- DNA Analysis of cells found in amniotic fluid.
As the list goes down it happens later in the pregnancy.
What are the advantages and disadvantages of Screening?
ADVANTAGES:
Money can be saved by not treating individuals with disorders who have been aborted.
Will prejudice occur?
Child and parents would avoid a potentially poor quality of life
DISADVANTAGES:
Screening is expensive
Embryo cannot give consent.
Screening can damage healthy individuals.
Lead to miscarriage